Boiler and elements therefor

ABSTRACT

A boiler element which, welded to similar elements, provides alternating fire ducts and water ducts separated by single, relatively thindividing walls. The dividing walls can be made relatively thin, and hence with optimum heat-transfer characteristics by virtue of the fact that they have a lateral, relatively short, rigid peripheral flange or ridge. The lateral ridges of adjacent elements are welded together to form a compact and undeformable peripheral wall for a water duct between two dividing walls.

United States Patent Schiffelers 1 Sept. 30, 1975 [54] BOILER AND ELEMENTS THEREFOR 3.366.092 1/1968 Bove 122/225 3,5 9,3 3 22 22 [75] Inventor: Theodoor Gerardus Maria 8 4 Luudm l 5 Schiffelers, Schaesberg, Netherlands [73] Assignee: Beondu A.G., Vaduz, Liechtenstein Emmmer l$enneth Sprague Attorney, Agent, or IIIHl-AllthOll}! A. O Brien [22] Filed: June 20, 1974 [2]] Appl. No.: 481,386

[57] ABSTRACT [30] Forelgn Apphcanon Pnonty Data A boiler element which, welded to similar elements, June 21, 1973 Netherlands 7308627 provides alternating fire ducts and water ducts sepa rated by single, relatively thindividing walls. The divid- [52] Cl 122/209 R; 22/223; 122/225 R; ing walls can be made relatively thin, and hence with 122/367 R optimum heat-transfer characteristics by virtue of the [51] lift. (,l. F22B 23/00 f that y have a lataral, relatively short, rigid P [58] held of Search 122/209- ripheral flange or ridge. The lateral ridges of adjacent 122/225 8 elements are welded together to form a compact and undeformable peripheral wall for a water duct be- [56] References C'ted tween two dividing walls.

UNITED STATES PATENTS 3.175.540 3/1965 Dubin et a1. 122/367 X 8 Claims, 3 Drawing Figures lg: '5 t i L r =h BOILER AND ELEMENTS THEREFOR This invention relates generally to a boiler for a central heating installation, and in particular to elements from which the boiler is composed.

Boilers to which the present invention pertains are built up from elements which, in combination, provide an arrangement of alternating fire ducts and ducts for a heat transferring fluid, such as water, the respective ducts being separated by a single heat-transferring dividing wall.

At the present time, gas-fired or oil-fired, central heating boilers have to satisfy severe, and often contradictory requirements. Thus their water content is required to be small so that there may be a fast on-off response, i.e., that the water in the installation is rapidly heated when fuel is ignited. Furthermore, design should be compact to make the boiler suitable for use in modern houses and flats, which often have only limited room for accommodating a boiler. Other requirements are a light weight and a high heat exchange efficiency, so that the temperature of the flue gases in the chimney is as low as possible.

A fast on-off response can be achieved when the dividing wall between the fire duct and the water duct is thin and made of light metal, which has a high heat exchange co-efficient. This also minimizes the weight of the boiler. However, a thin wall of light metal, for example, cast in aluminium, is generally insufficiently strong to withstand the relatively high water pressures. This could be remedied by minimizing the surface areas of the heat-transferring walls, but then this is in conflict with the requirement of efficient heat exchange and low flue gas temperatures.

It is an object of the present invention to provide a solution for the afore-described problems.

According to the invention, in a central heating boiler comprising boiler elements which in combination provide at least one fire duct and at least one water duct separated by a single dividing wall, each boiler element is cast in one piece in the form of a hollow flat box which, placed in upright position, has an open top and an open bottom each closable with a cover member, a narrow front wall, a narrow rear wall and broad sidewalls defining a fire duct between them, said sidewalls being provided on the inside with heat absorbing members extending from said side walls into said fire duct, and being shaped on the outside so that in two adjacent boiler elements joined in side-by-side relationship their facing side walls define a water duct between them which additionally is peripherally bounded by a narrow, non-deformable peripheral wall having an unbendable connection with the adjoining sidewalls.

In a boiler composed of elements according to the invention, the water ducts are very narrow, so that the requirement of a low water content is complied with, and the requirement of a compact design is met to a great extent. The elements can be formed, for example, of aluminium even if their sidewalls are relatively thin, by virtue of the unbendable connection with the narrow peripheral wall, as a result of which deflection of the dividing walls under the influence of the water pressure is prevented by the virtually undeformable peripheral wall.

A narrow, undeformable peripheral wall for each water duct can be achieved in a structurally simple manner by providing each of the sidewalls of the boiler elements on the outside with a peripheral flange which in cross-section is approximately as high as broad, and which constitutes one half of a peripheral wall for a water duct, said flange having an unbendable connection with the associated sidewall of the boiler elements.

When two boiler elements are placed in side-by-side relationship and welded together at their adjoining peripheral flanges a narrow, thick peripheral wall for a water duct is formed. Deflection of a dividing wall by water pressure is effecitively prevented owing to the fact that such deflection is unable to effect a corresponding deflection into the water duct, of the rigid peripheral wall of the water duct. Such inward deflection of the peripheral wall is additionally prevented by the water pressure, which also acts on said peripheral wall.

Preferably, according to the invention, the peripheral flange has a bevelled or rounded base on its side facing the water duct.

According to another preferred feature of the invention the peripheral flange has a recessed top on its side away from the water duct, so that when two elements are joined there is provided a peripheral recess for receiving a run of weld metal.

Additional preferred features of the present invention are that, for additional reinforcement of the sidewalls of the boiler element, said side walls are each provided on the side of the water duct with substantially horizontal ribs defining a labyrinth passage for water, and on the side of the fire duct with undulated substantially vertically extending ribs which increase the heated surface area, while the two sidewalls of the element are interconnected by water passage tubes integral with the element.

One embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a vertical sectional view, on the lines I I of FIG. 2, of two elements according to the invention, welded together in side-by-side relationship;

FIG. 2 is a side elevational view of the sub-assembly of FIG. 1 with a part being broken away and;

FIG. 3 is a top plan view of FIG. 2 with a part broken away.

Referring to the drawings, there are shown two welded-together boiler elements 1, each of which has sidewalls 2, front and rear walls 3 and an open top and an open bottom. Each element defines a fireduct on the inside, and each sidewall is formed with substantially vertical, undulated ribs 4, extending from the sidewall into the fire duct and increasing the heated surface area. Element 1 is formed on the outside with horizontal ribs 5 which in two joined elements link with one another to define a labyrinth passage for water or another heat transferring medium in a water duct. The water ducts are connected together by passages 6. A boiler is equipped with at least two joined elements, covered at the end sidewalls with covers (not shown).

In addition to the horizontal ribs 5, the sidewalls of each element 1 are provided on the side of the water duct with a peripheral flange 7 which in cross-section is approximately as high as broad. Peripheral flange 7 connects on the inside to the adjoining sidewall 2 via a bevel or rounding 8. On the outside flange 7 is bevelled, such as by milling, for example at an angle of 45, so that when two elements are joined a groove is formed for receiving a run of welding metal 9.

In the subassembly of two boiler elements shown in FIG. 1, the water duct located in between the elements is defined on opposite sides by flat sidewalls 2 and in the peripheral direction by a narrow peripheral wall constituted by two peripheral flanges 7. Owing to the fact that the flanges 7 are of compact design and have an unbendable connection with the flat walls 2, sidewalls 2 can be made relatively thin. For deflection of sidewalls 2 under the influence of water pressure is effectively opposed by peripheral wall 7. Thin sidewalls 2 between a water duct and fire ducts ensure rapid response upon ignition and efficient exchange of heat, and additionally minimize the weight of the boiler.

It will be clear that in a boiler composed of a number of boiler elements according to the invention, for example, four, the extreme sidewalls 2 are closed, in a manner well-known per se, with flat covers provided with stubs for the supply and discharge of water.

Practice has shown that with an element 1 cast of aluminium with sidewalls 2 of 300 X 300 X 6 mm, a pcripheral flange 7 with a height of 7 mm, i.e., a water duct l4 mm wide, and a fire duct 45 mm wide and 300 mm high, a fall in temperature from l500C to about 200C is achieved in a length of flue of 30 cm while 8000 Kcal/h is given off to the water per element.

A boiler composed of such elements, including flue and space for a burner is not more than 60 cm high. Its depth, determined by the size of the boiler elements and additionally by the room necessary for installing a boiler water thermostat, a gas control block and other appurtenances, need not be more than about 50 cm. The width of the boiler, determined by the number of elements, is about 35 cm with a capacity of 32,000 Kcal/h. In this example the boiler can easily withstand gauge pressures of 4 ats; it is pressure-tested at a gauge pressure of 12 ats.

I claim:

1. A boiler element which when connected to similar boiler elements provides a plurality of alternating fire ducts and water ducts separated by a single wall, characterized by said boiler element being cast in one piece in the form of a hollow flat box which, placed in upright position, has an open top and an open bottom; a narrow front wall, a narrow rear wall and broad sidewalls defining a fire duct between them; heat absorbing members extending from said sidewalls into said fire duct; and said sidewalls being of such configuration on the side away from said fire ducts that in two joined elements the opposing sidewalls define a water duct between them which in addition to said sidewalls is peripherally bounded by a narrow, non-deformable peripheral wall having an unbendable connection with the respective adjacent sidewalls.

2. A boiler element according to claim 1, wherein the sidewalls are each formed on the side away from the fire duct with a peripheral flange which in cross-section is approximately as high as broad, and which constitutes one half of aperipheral wall for a water duct, said flange having an unbendable connection with the associated sidewall of the element.

v 3. A boiler element according to claim 2, wherein said peripheral flange has a bevelled or rounded base on its side facing the water duct.

4. A boiler element according to claim 2, wherein said peripheral flange is bevelled on its side away from the water duct, so that when two elements are joined there is provided a peripheral recess for receiving a run of weld metal.

. 5. A boiler element according to claim 1, wherein each sidewall is provided on the side away from the fire duct with substantially horizontal ribs defining a labyrinth passage for water, and on the side facing the fire duct with undulated, substantially vertically extending ribs increasing the surface area to be heated, and the two sidewalls of the element being interconnected by water passage tubes integral with the element.

6. In a boiler for use in a central heating installation, a subassembly of boiler elements connected together to provide at least one water duct and at least one fire duct separated by a single wall, each of said boiler elements being cast in one piece in the form of a hollow flat box which, placed in upright position, has an open top and an open bottom each closable with a cover member, a narrow front wall, a narrow rear wall and broad sidewalls defining afire duct between them, said sidewalls being provided on the side facing said fire duct with heat absorbing members extending from saidsidewallsinto said first duct, and being shaped on the outside so that in two adjacent boiler elements joinedin side-by-side relationship their facing sidewalls define a water duct between them which additionally is peripherally bounded by a narrow, non-deformable peripheral wall having an unbendable connection with the adjoining sidewalls. I I

7. In a boiler for use in a central heating installation, a subassembly of boiler elements welded together to provide at least one water duct and at least one fire duct separated by a single wall, each of said boiler elements being cast in one piece in the form of a hollow flat box which, placed in upright position, has an open top and an open bottom each closable with a cover member, a narrow front wall, a narrow rear wall and broad sidewalls defining a fire duct between them, said sidewalls being formed on the side facing said fire duct with heat absorbing projections extending into said fire duct, and on the side away from said fire duct with a pattern of projections which together with corresponding projections formed on the opposing side of an adjacent element provide a curved water passage in a water duct formed between said opposing sides of the adjacent elements and a narrow non-deformable peripheral wall formed by peripherally welding together opposing peripheral flanges integral with the respective elements and formed on the sides away from said fire duct.

8. Ina boiler for use in a central heating installation, a subassembly of boiler elements welded together to provide at least one water duct and at least one fire duct separated by a. single wall, each of said boiler elements beingcast in one piece in the form of a hollow, flat box which, placed in upright position, has an open top and an open bottom each closable with a cover member, a narrow front wall, a narrow rear wall and broad sidewalls defining a fire duct between them, said sidewalls being formed on the side facing said fire duct with undulated, substantially vertically extending ribs increasing the surface area to be heated, and on the side away from said fire duct with substantially horizontal ribs which together with correspondingribs formed on the opposing side of an adjacent element provide a curved water passage in a water duct formed between said opposing sides of the adjacent elements and a narrow, non-deformable, peripheral wall formed by peripherally welding together opposing peripheral flanges a run of weld metal for joining two elements together, the water ducts formed between the respective elements being interconnected by water passage tubes integral with the respective elements. 

1. A boiler element which when connected to similar boiler elements provides a plurality of alternating fire ducts and water ducts separated by a single wall, characterized by said boiler element being cast in one piece in the form of a hollow flat box which, placed in upright position, has an open top and an open bottom; a narrow front wall, a narrow rear wall and broad sidewalls defining a fire duct between them; heat absorbing members extending from said sidewalls into said fire duct; and said sidewalls being of such configuration on the side away from said fire ducts that in two joined elements the opposing sidewalls define a water duct between them which in addition to said sidewalls is peripherally bounded by a narrow, nondeformable peripheral wall having an unbendable connection with the respective adjacent sidewalls.
 2. A boiler element according to claim 1, wherein the sidewalls are each formed on the side away from the fire duct with a peripheral flange which in cross-section is approximately as high as broad, and which constitutes one half of a peripheral wall for a water duct, said flange having an unbendable connection with the associated sidewall of the element.
 3. A boiler element according to claim 2, wherein said peripheral flange has a bevelled or rounded base on its side facing the water duct.
 4. A boiler element according to claim 2, wherein said peripheral flange is bevelled on its side away from the water duct, so that when two elements are joined there is provided a peripheral recess for receiving a run of weld metal.
 5. A boiler element according to claim 1, wherein each sidewall is provided on the side away from the fire duct with substantially horizontal ribs defining a labyrinth passage for water, and on the side facing the fire duct with undulated, substantially vertically extending ribs increasing the surface area to be heated, and the two sidewalls of the element being interconnected by water passage tubes integral with the element.
 6. In a boiler for use in a central heating installation, a subassembly of boiler elements connected together to provide aT least one water duct and at least one fire duct separated by a single wall, each of said boiler elements being cast in one piece in the form of a hollow flat box which, placed in upright position, has an open top and an open bottom each closable with a cover member, a narrow front wall, a narrow rear wall and broad sidewalls defining a fire duct between them, said sidewalls being provided on the side facing said fire duct with heat absorbing members extending from said sidewalls into said first duct, and being shaped on the outside so that in two adjacent boiler elements joined in side-by-side relationship their facing sidewalls define a water duct between them which additionally is peripherally bounded by a narrow, non-deformable peripheral wall having an unbendable connection with the adjoining sidewalls.
 7. In a boiler for use in a central heating installation, a subassembly of boiler elements welded together to provide at least one water duct and at least one fire duct separated by a single wall, each of said boiler elements being cast in one piece in the form of a hollow flat box which, placed in upright position, has an open top and an open bottom each closable with a cover member, a narrow front wall, a narrow rear wall and broad sidewalls defining a fire duct between them, said sidewalls being formed on the side facing said fire duct with heat absorbing projections extending into said fire duct, and on the side away from said fire duct with a pattern of projections which together with corresponding projections formed on the opposing side of an adjacent element provide a curved water passage in a water duct formed between said opposing sides of the adjacent elements and a narrow non-deformable peripheral wall formed by peripherally welding together opposing peripheral flanges integral with the respective elements and formed on the sides away from said fire duct.
 8. In a boiler for use in a central heating installation, a subassembly of boiler elements welded together to provide at least one water duct and at least one fire duct separated by a single wall, each of said boiler elements being cast in one piece in the form of a hollow, flat box which, placed in upright position, has an open top and an open bottom each closable with a cover member, a narrow front wall, a narrow rear wall and broad sidewalls defining a fire duct between them, said sidewalls being formed on the side facing said fire duct with undulated, substantially vertically extending ribs increasing the surface area to be heated, and on the side away from said fire duct with substantially horizontal ribs which together with corresponding ribs formed on the opposing side of an adjacent element provide a curved water passage in a water duct formed between said opposing sides of the adjacent elements and a narrow, non-deformable, peripheral wall formed by peripherally welding together opposing peripheral flanges integral with the respective elements and formed on the sides away from said fire duct, each peripheral flange having a bevelled or rounded base on its side facing the water duct and a recessed top on its side away from the water duct to provide a peripheral recess for receiving a run of weld metal for joining two elements together, the water ducts formed between the respective elements being interconnected by water passage tubes integral with the respective elements. 